INBDE Periodontics Practice Exam 2026
| 100 Advanced Questions & Answers
with Detailed Rationales | Integrated
National Board Dental Examination
Prep & Study Guide
1. A patient presents with generalized bleeding on probing, 5–6 mm probing
depths, clinical attachment loss, and radiographic horizontal bone loss.
There is no history of systemic disease or smoking. Which diagnosis best
describes this condition?
A. Gingivitis
B. Periodontitis
C. Necrotizing periodontal disease
D. Periodontal abscess
Answer: Periodontitis
Rationale: Clinical attachment loss associated with periodontal pocketing and
radiographic alveolar bone loss establishes periodontitis rather than gingivitis.
2. Which finding most directly distinguishes periodontitis from plaque-
induced gingivitis?
,A. Gingival erythema
B. Bleeding on probing
C. Clinical attachment loss caused by periodontal destruction
D. Dental plaque accumulation
Answer: Clinical attachment loss caused by periodontal destruction
Rationale: Gingivitis is confined to the gingival tissues, whereas periodontitis
involves destruction of the periodontal attachment apparatus.
3. A patient has interdental clinical attachment loss of 3 mm at several
nonadjacent teeth and a maximum probing depth of 5 mm. Radiographs
demonstrate bone loss extending to the coronal third of the root. Which
staging characteristic is most consistent with this presentation?
A. Stage I
B. Stage II
C. Stage III
D. Stage IV
Answer: Stage III
Rationale: Stage III periodontitis includes more substantial attachment and
bone loss and may involve probing depths of 6 mm or greater, vertical bone loss,
furcation involvement, or other complexity factors. Staging requires assessment
of the overall disease complexity rather than a single measurement.
4. Which microorganism is classically associated with localized aggressive
periodontal destruction in younger patients?
A. Streptococcus mutans
B. Aggregatibacter actinomycetemcomitans
C. Lactobacillus acidophilus
D. Candida albicans
Answer: Aggregatibacter actinomycetemcomitans
,Rationale: A. actinomycetemcomitans has historically been strongly associated
with localized aggressive periodontitis, particularly because of virulence factors
such as leukotoxin.
5. What is the primary initiating factor in plaque-induced periodontal
inflammation?
A. Occlusal trauma
B. Dental biofilm
C. Bruxism
D. Root morphology
Answer: Dental biofilm
Rationale: Dental biofilm provides the microbial stimulus that initiates the host
inflammatory response. Other factors can modify disease severity but do not
replace biofilm as the primary etiologic factor.
6. Which immunoglobulin is the predominant antibody in gingival crevicular
fluid?
A. IgA
B. IgD
C. IgE
D. IgG
Answer: IgG
Rationale: IgG is abundant in gingival crevicular fluid and contributes to immune
defense against periodontal microorganisms.
7. A patient has a periodontal pocket measuring 6 mm. The gingival margin is
located 2 mm apical to the cementoenamel junction. What is the clinical
attachment level?
A. 4 mm
B. 6 mm
, C. 8 mm
D. 10 mm
Answer: 8 mm
Rationale: When the gingival margin is apical to the CEJ, the recession depth is
added to the probing depth. Therefore, 6 mm + 2 mm = 8 mm clinical
attachment loss.
8. A periodontal probe penetrates the junctional epithelium during probing.
Which factor most influences the measured probing depth?
A. Enamel thickness
B. Degree of gingival inflammation
C. Tooth color
D. Pulp vitality
Answer: Degree of gingival inflammation
Rationale: Inflamed periodontal tissues provide less resistance to probe
penetration, which can increase probing depth measurements compared with
healthy tissues.
9. Which radiographic finding is most characteristic of chronic periodontal
destruction?
A. Periapical radiolucency only
B. Widening of the pulp chamber
C. Crestal alveolar bone loss
D. Hypercementosis
Answer: Crestal alveolar bone loss
Rationale: Periodontal disease produces loss of alveolar supporting bone,
commonly appearing as horizontal or vertical/angular bone loss on radiographs.
10.Which radiographic technique is generally preferred for evaluating
posterior alveolar crest height and periodontal bone levels?
| 100 Advanced Questions & Answers
with Detailed Rationales | Integrated
National Board Dental Examination
Prep & Study Guide
1. A patient presents with generalized bleeding on probing, 5–6 mm probing
depths, clinical attachment loss, and radiographic horizontal bone loss.
There is no history of systemic disease or smoking. Which diagnosis best
describes this condition?
A. Gingivitis
B. Periodontitis
C. Necrotizing periodontal disease
D. Periodontal abscess
Answer: Periodontitis
Rationale: Clinical attachment loss associated with periodontal pocketing and
radiographic alveolar bone loss establishes periodontitis rather than gingivitis.
2. Which finding most directly distinguishes periodontitis from plaque-
induced gingivitis?
,A. Gingival erythema
B. Bleeding on probing
C. Clinical attachment loss caused by periodontal destruction
D. Dental plaque accumulation
Answer: Clinical attachment loss caused by periodontal destruction
Rationale: Gingivitis is confined to the gingival tissues, whereas periodontitis
involves destruction of the periodontal attachment apparatus.
3. A patient has interdental clinical attachment loss of 3 mm at several
nonadjacent teeth and a maximum probing depth of 5 mm. Radiographs
demonstrate bone loss extending to the coronal third of the root. Which
staging characteristic is most consistent with this presentation?
A. Stage I
B. Stage II
C. Stage III
D. Stage IV
Answer: Stage III
Rationale: Stage III periodontitis includes more substantial attachment and
bone loss and may involve probing depths of 6 mm or greater, vertical bone loss,
furcation involvement, or other complexity factors. Staging requires assessment
of the overall disease complexity rather than a single measurement.
4. Which microorganism is classically associated with localized aggressive
periodontal destruction in younger patients?
A. Streptococcus mutans
B. Aggregatibacter actinomycetemcomitans
C. Lactobacillus acidophilus
D. Candida albicans
Answer: Aggregatibacter actinomycetemcomitans
,Rationale: A. actinomycetemcomitans has historically been strongly associated
with localized aggressive periodontitis, particularly because of virulence factors
such as leukotoxin.
5. What is the primary initiating factor in plaque-induced periodontal
inflammation?
A. Occlusal trauma
B. Dental biofilm
C. Bruxism
D. Root morphology
Answer: Dental biofilm
Rationale: Dental biofilm provides the microbial stimulus that initiates the host
inflammatory response. Other factors can modify disease severity but do not
replace biofilm as the primary etiologic factor.
6. Which immunoglobulin is the predominant antibody in gingival crevicular
fluid?
A. IgA
B. IgD
C. IgE
D. IgG
Answer: IgG
Rationale: IgG is abundant in gingival crevicular fluid and contributes to immune
defense against periodontal microorganisms.
7. A patient has a periodontal pocket measuring 6 mm. The gingival margin is
located 2 mm apical to the cementoenamel junction. What is the clinical
attachment level?
A. 4 mm
B. 6 mm
, C. 8 mm
D. 10 mm
Answer: 8 mm
Rationale: When the gingival margin is apical to the CEJ, the recession depth is
added to the probing depth. Therefore, 6 mm + 2 mm = 8 mm clinical
attachment loss.
8. A periodontal probe penetrates the junctional epithelium during probing.
Which factor most influences the measured probing depth?
A. Enamel thickness
B. Degree of gingival inflammation
C. Tooth color
D. Pulp vitality
Answer: Degree of gingival inflammation
Rationale: Inflamed periodontal tissues provide less resistance to probe
penetration, which can increase probing depth measurements compared with
healthy tissues.
9. Which radiographic finding is most characteristic of chronic periodontal
destruction?
A. Periapical radiolucency only
B. Widening of the pulp chamber
C. Crestal alveolar bone loss
D. Hypercementosis
Answer: Crestal alveolar bone loss
Rationale: Periodontal disease produces loss of alveolar supporting bone,
commonly appearing as horizontal or vertical/angular bone loss on radiographs.
10.Which radiographic technique is generally preferred for evaluating
posterior alveolar crest height and periodontal bone levels?
